Magnetic amplifiers have been well known in the art for use in power control systems. Magnetic amplifiers rely on the fact that magnetic fields or magnetic bias are created in the magnetic circuits of inductive power components so as to effect the control of current or power. It is known in the prior art to construct magnetic inductors containing an iron core, such as disclosed in U.S. Pat. Nos. 4,103,221 and 4,009,460, both to Fukui et al. However, when an inductor utilizes a ferromagnetic core for example, the core is readily capable of reaching magnetic saturation, due to DC electric current, resulting in a reduction of the inductance. To avoid these saturation problems, Fukui et al. proposes to utilize permanent magnetic cores for the inductors, with such cores producing a permanent biasing magnetic field. By doing so, the core of the inductor is less likely to suffer magnetic saturation and has an extended range of useful inductance. However, the devices as described by Fukui et al. form a solid core structure, and are thus still heavy and are not well adapted for devices where a reduction of weight is critical. In addition, the devices of Fukui generally do not maintain a precise and steady level of flux density or saturation, throughout a wide range of DC current. Furthermore, the device of Fukui are specifically designed for DC current applications, and do not appear to be effective in AC current applications.
In addition, magnetic devices such as transformers, chokes and inductors commonly used silicon grade steel for the magnetic core and copper or aluminum for the windings. Over the last decades, this technology has not progressed but improvements have been made in materials and processes for the constructions of such transformers. However, a need still remains for magnetic technology with reduced energy loss characteristics, reduced weight and lower cost. A need also exists for energy efficient and cost efficient transformers which can be utilized in high power consumption circuits, such as ballasts for street lighting and are discharge lamp applications, or circuits used in current, power control and distribution.